Brain microvessels are innervated by locus ceruleus noradrenergic neurons

Noradrenergic fibers from the locus ceruleus were identified in close proximity to brain microvessels, and adrenoceptors exist in isolated brain capillaries. Yet, proof of innervation of brain microvessels by locus ceruleus remains elusive. We now demonstrate increased density of beta-adrenoceptors by pindolol binding in microvessels isolated from the norepinephrine-depleted cerebrum two weeks after locus ceruleus lesion or reserpine treatment. This finding of 'denervation supersensitivity' in brain microvessels implies that their adrenoceptors respond to norepinephrine from the locus ceruleus, and strongly suggests that the locus ceruleus innervates brain microvessels. These results may have important implications because blood-brain barrier dysfunction may be a factor in the pathophysiology of Alzheimer dementia and Parkinson disease, which are associated with locus ceruleus degeneration.     

The cornea is not innervated by substance P-containing primary afferent neurons

The contribution of substance P-containing primary afferent neurons to the innervation of two pain sensitive organs, the skin and the cornea, was investigated in rats. A combined fluorochrome tracing-immunohistochemical method was used. While 8.4% of the sensory neurons innervating the skin of the neck display substance P immunoreactivity, the cornea lacks any substance P-immunostained primary afferents.     

Colocalization of parvalbumin and calbindin D-28k in neurons including chandelier cells of the human temporal neocortex

Chandelier cells are cortical GABAergic interneurons with a unique synaptic specificity enabling them to exert a strong inhibitory influence on pyramidal cells. By using immunocytochemistry for the calcium-binding protein calbindin D-28k in the human temporal neocortex, we have found numerous immunoreactive processes that were identified as chandelier cell axon terminals. This was a striking find since in previous immunocytochemical studies of the primate neocortex, chandelier cell axon terminals had been shown to be immunoreactive for another calcium-binding protein, parvalbumin, and colocalization studies indicate that parvalbumin and calbindin are present in almost completely separate neuronal populations. Here, we present double-label immunofluorescence experiments showing that parvalbumin and calbindin immunoreactivities are colocalized in certain neurons that include a subpopulation of chandelier cells whose cell bodies are located mainly in layers V and VI of the human temporal neocortex. The results suggest a selective laminar distribution of neurochemical subtypes of chandelier cells which is a peculiar feature of the organization of the human neocortex.     

腰骶神经根感觉分布区的临床研究

目的：确定腰骶神经根的感觉分布区。方法：对１６６名因腰椎间盘突出症引起Ｌ４～Ｓ１单根神经根损害的患者进行检查,记录其下肢感觉障碍区的范围。结果：Ｌ４～Ｓ１神经根损害皮肤感觉障碍区分别以膝及小腿内侧、足背第１、２趾之间及足底最外侧最为常见,因此为这些神经根的自主区。结论：感觉检查对于腰骶神经根损害的定位诊断具有重要意义,而自主区的感觉检查可简化诊断过程,结果也更为可靠     

Reticular groove and reticulum are innervated by myenteric neurons with different neurochemical codes

The reticulum and the reticular groove are functional distinct compartments within the ovine forestomach. While the reticulum takes part in various motor functions, such as mixing, retaining, and rejecting the forestomach ingesta, the reticular groove serves mainly as a bypass between the esophagus and the abomasum. To accomplish these different tasks, the compartments develop specific motility patterns that are controlled by intrinsic neural circuits. In this study the intrinsic innervation by myenteric neurons was analyzed by quadruple immunohistochemistry against cholineacetyl transferase (ChAT), nitric oxide synthase (NOS), substance P (SP), and vasoactive intestinal peptide (VIP). Four neurochemically different subpopulations of myenteric neurons were found in the reticulum and the floor of the reticular groove: ChAT/-, ChAT/SP, NOS/-, and NOS/VIP. The neuronal proportions were calculated relative to all myenteric neurons. Neurons of the reticulum were mostly immunoreactive for ChAT (89% +/- 3%), whereas neurons adjacent to the reticular groove predominantly expressed a nitrergic phenotype (62% +/- 4%). ChAT-positive neurons were also immunoreactive for SP (ChAT/SP: 64% +/- 3% reticulum; 25% +/- 1% reticular groove) or were purely cholinergic (ChAT/-: 25% +/- 4% reticulum; 13% +/- 3% reticular groove). NOS-positive neurons colocalized VIP (NOS/VIP: 10% +/- 3% reticulum; 46% +/- 1% reticular groove) or none of the other neurotransmitters (NOS/-: 1% +/- 1% reticulum; 17% +/- 3% reticular groove). Analysis of the soma sizes revealed that in both compartments the nitrergic neurons were significantly larger than the cholinergic neurons. It is suggested that the specific neurochemical code in combination with a specific morphology leads to a precise regulation of the specialized tasks of the reticulum and reticular groove by subpopulations of myenteric neurons.     

Spatial distribution of various types of bulbar respiratory neurons in the rabbit

Summary In anesthetized rabbits, the burst activity of 277 single respiratory neurons was recorded extracellularly. The neurons were classified according to their spike incidence distribution within the respiratory cycle and to their response to lung distension or collapse ( or type). About one third of the neurons found in all animals were located at the level of the caudal end of the promontorium gliosum, widely scattered over the bulbar cross-section. More rostrally the units were located within a dorsal area neighbouring the tractus solitarius, more caudally within a ventral field surrounding the nucleus ambiguus. Most of the inspiratory neurons (the most frequently encountered type) were found within an antero-medial region of the medulla, extending down to about two thirds of its depth. Most of the inspiratory-expiratory units were found within an intermediate zone extending from antero-dorsal to postero-ventral. Most of the expiratory cells were found postero-ventrally. Most of the expiratory-inspiratory neurons (the rarest type) were again found within an antero-medial region at an intermediate depth. The neurons were located in the rostral and the units in the caudal part of the medulla. The average proportion of respiratory neurons to non-respiratory units was estimated as about 1:36 and the total number of bulbar respiratory neurons as 500 on each side.     

Experimental evidence indicating that the penis of the rat is innervated by short adrenergic neurons

To determine if the penis of the rat is supplied by long or short adrenergic neurons, hypogastric and perivascular neurectomies were performed. Reserpine, a drug which depletes the store of norepinephrine from long adrenergic nerves more rapidly than from short adrenergic neurons, has also been used to aid in characterizing this innervation. Hypogastric neurectomy, with or without denervation of the common iliac vessels, had no effect on the density or fluorescence intensity of adrenergic fibers in the rat penis. The long adrenergic fibers to the atria did not fluoresce in reserpine-treated rats; however, fluorescent adrenergic fibers in the penis and vas deferens remained visible. Reserpine depressed atrial levels of norepinephrine by 75%, while norepinephrine in the penis and vas deferens was reduced only by 32% and 29%, respectively. The absence of any effect of hypogastric neurectomy on the adrenergic fibers of the penis indicates that such fibers arise from neurons distal to the site of lesion of the hypogastric nerves. This result and the similar response of the vas deferens and penis to reserpine strongly suggest that the penis of the rat is supplied by short adrenergic neurons.     

Spatial distribution of the vestibulospinal neurons in the frog vestibular nuclei.

In experiments on the preparation of a frog perfused brain (Rana ridibunda), intracellular potentials were recorded from neurons of the vestibular nuclei following stimulation of the vestibular nerve and the spinal cord. The vestibulospinal neurons were identified on the basis of excitatory postsynaptic potentials evoked by the stimulation of the ipsilateral vestibular nerve and antidromic activation from the stimulation of the cervical and lumbar enlargements of the spinal cord. The cells that could be activated antidromically only by cervical cord stimulation have been designated as C cells, and the cells that could also be activated antidromically as a result of lumbar stimulation have been termed L cells. The average conduction velocity determined for C neurons was 10.67 m/s and for L neurons 15.84 m/s. The ratio of C and L neurons over the vestibular nuclear complex was very similar to each other: 52% C neurons and 48% L neurons. The majority of both types of neurons were localized in the lateral vestibular nucleus (58.6%), to a lesser extent in the descending vestibular nucleus (30.7%) and very little in the medial vestibular nucleus (10.6%). In the lateral vestibular nucleus, C neurons prevailed in the caudal part of the nucleus and L neurons prevailed in the rostral part. By contrast, in the descending and medial vestibular nuclei there was a gradual increase of C and L cells quantitatively from the rostral to the caudal part. Fast and slow cells were detected among the vestibulospinal neurons. The fast neurons of L cells did not prevail greatly over the slow ones, whereas the slow neurons of C cells prevailed comparatively largely over the fast neurons. Thus, it became possible to reconstruct the spatial distribution of the identified vestibulospinal neurons. The results of spatial distribution of C and L vestibulospinal neurons in the frogs failed to conform to definite somatotopy, which is characteristic of mammalian vestibular nuclei.The results of this study have confirmed an earlier assumption that C and L neurons in the frog's vestibular nuclei as a source of vestibulospinal fibers, are scattered separately or more frequently in groups, so that they establish a 'patch-like' somatotopy and do not form a distinctly designed field as in mammals.     

Tremorgenesis: a new conceptual scheme using reciprocally innervated circuit of neurons

Neural circuits controlling fast movements are inherently unsteady as a result of their reciprocal innervation. This instability is enhanced by increased membrane excitability. Recent studies indicate that the loss of external inhibition is an important factor in the pathogenesis of several tremor disorders such as essential tremor, cerebellar kinetic tremor or parkinsonian tremor. Shaikh and colleagues propose a new conceptual scheme to analyze tremor disorders. Oscillations are simulated by changing the intrinsic membrane properties of burst neurons. The authors use a model neuron of Hodgkin-Huxley type with added hyperpolarization activated cation current (I_h), low threshold calcium current (I_t), and GABA/glycine mediated chloride currents. Post-inhibitory rebound is taken into account. The model includes a reciprocally innervated circuit of neurons projecting to pairs of agonist and antagonist muscles. A set of four burst neurons has been simulated: inhibitory agonist, inhibitory antagonist, excitatory agonist, and excitatory antagonist. The model fits well with the known anatomical organization of neural circuits for limb movements in premotor/motor areas, and, interestingly, this model does not require any structural modification in the anatomical organization or connectivity of the constituent neurons. The authors simulate essential tremor when I_h is increased. Membrane excitability is augmented by up-regulating I_h and I_t. A high level of congruence with the recordings made in patients exhibiting essential tremor is reached. These simulations support the hypothesis that increased membrane excitability in potentially unsteady circuits generate oscillations mimicking tremor disorders encountered in daily practice. This new approach opens new perspectives for both the understanding and the treatment of neurological tremor. It provides the rationale for decreasing membrane excitability by acting on a normal ion channel in a context of impaired external inhibition.     

Synaptic connections of axo-axonic (chandelier) cells in human epileptic temporal cortex

The human temporal cortex contains a type of interneuron, identified by Golgi impregnation which, like the axo-axonic or chandelier cells found in animals, establishes Gray's type II synaptic contacts exclusively with the axon initial segments of pyramidal cells. Each terminal segment is composed of 3-12 boutons to form a "chandelier"-like appearance. For the two human axo-axonic cells analysed in this study we could identify 269 and 86 bouton rows respectively, which represents an equivalent number of postsynaptic pyramidal cells. A terminal bouton row from one of these Golgi-impregnated cells was shown to be in synaptic contact with the axon initial segment of a Golgi-impregnated pyramidal cell. The very specific nature of the target of axo-axonic cells, together with their highly divergent axonal arborization, means that they are ideally placed to control the output of a large population of pyramidal cells. Since previous studies in animals have shown the GABAergic nature of axo-axonic cells it is possible that human axo-axonic cells could be involved in the generation of epileptic activity or in the control of its propagation.     

Interstitial cells of Cajal are functionally innervated by excitatory motor neurones in the murine intestine

Recent studies have demonstrated that intramuscular interstitial cells of Cajal (ICC) are preferential targets for neurotransmission in the stomach. Terminals of enteric motor neurones also form tight, synaptic-like contacts with ICC in the small intestine and colon, but little is known about the role of these cells in neurotransmission. ICC at the deep muscular plexus (ICC-DMP) of the small intestine express neurokinin 1 receptors (NK1R) and internalize these receptors in response to exogenous substance P. We used NK1R internalization as an assay of functional innervation of ICC-DMP in the murine small intestine. Under basal conditions NK1R-like immunoreactivity (NK1R-LI) was mainly observed in ICC-DMP (519 cells counted, 100% were positive) and myenteric neurones. ICC-DMP were closely apposed to substance P-containing nerve fibres. Of 338 ICC-DMP examined, 65% were closely associated with at least one substance P-positive nerve fibre, 32% were associated with at least two, 2% were associated with more than two nerve fibres and 1% with none. After electrical field stimulation (EFS, 10 Hz; 1 min) NK1R-LI was internalized in more than 80% of ICC-DMP, as compared to 10% of cells before EFS. Internalization of NK1R was not observed in myenteric ICC or smooth muscle cells in response to nerve stimulation. Internalization of NK1R-LI was blocked by the specific NK1 receptor antagonist WIN 62577 (1 μ m ) and by tetrodotoxin (0.3 μ m ), suggesting that internalization resulted from stimulation of receptors with neurally released neurokinins. These data suggest that ICC-DMP are primary targets for neurokinins released from enteric motor neurones in the intestine.     

Spatial properties of central vestibular neurons

We studied the spatial characteristics of 45 vestibular-only (VO) and 12 vestibular-plus-saccade (VPS) neurons in two cynomolgus monkeys using angular rotation and static tilt. The purpose was to determine the contribution of canal and otolith-related inputs to central vestibular neurons whose activity is associated with the central velocity storage integrator. Lateral canal-related neurons responded maximally during vertical axis rotation when the head was tilted 25 +/- 6 and 22 +/- 3 degrees forward relative to the axis of rotation in the two animals, and vertical canal-related neurons responded maximally with the head tilted back 63+/- 5 and 57 +/- 7 degrees . The origin of the vertical canal-related input was verified by rotation about a spatial horizontal axis. Thirty-one percent of cells received input in a single canal plane. Sixty-seven percent of canal-related cells received otolith input, 31% of vertical canal neurons had lateral canal input, and 43% of lateral canal neurons had vertical canal input. Twenty percent of neurons had convergent input from the lateral canals, the vertical canals, and the otolith organs. Some VO and VPS cells had spatial-temporal convergent (STC) properties; more of these cells had STC properties at lower frequencies of rotation. Thus VO and VPS neurons associated with velocity storage receive a broad range of convergent inputs from each portion of the vestibular labyrinth. This convergence could provide the basis for gravity-dependent eye velocity orientation induced through velocity storage.     

Spatial distribution of DNA-synthesizing cells in colonic crypts of the guinea pig

The ascending colon of a guinea pig injected with tritiated thymidine was cut serially, autoradiographed and stained with periodic-acid-Schiff-hematoxylin. Maps of transversely sectioned crypts were prepared with the use of a microscope eye-piece projector. The number and angular positions of pulselabelled (DNA-synthesizing) cells around the circumference of transverse sections of the crypt were recorded. A method of “statistics of the circumference” was applied in order to find the variances of angular distances between labelled cells and thereby to find the type of arrangement of DNA-synthesizinbg cells in the crypt. The spatial distribution of DNA-synthesizing cells, both around the crypt circumference and along the crypt, was found to be non-random. While the pattern of nonrandomness around the crypt circumference is such that the DNA-synthesizing cells tend to occupy positions in the crypt circumference at maximal distances from each other, DNA-synthesizing cells along the crypt tend to occupy positions at minimal distances from each other. DNA-synthesizing cells are arranged in the crypt in rows, each consisting of several cells and each parallel to the long axis of the crypt. Apparently the dividing cell of the crypt produces either two proliferating or two differentiating cells. No evidence of differential mitosis could be found.     

The dorsal portion of the lumbar intervertebral disc is innervated primarily by small peptide-containing dorsal root ganglion neurons in rats

The intervertebral discs are innervated by the dorsal root ganglion (DRG) neurons. In the present study, we applied Fluoro-Gold (FG) to the dorsal portion of the L5-L6 intervertebral disc to label DRG neurons retrogradely, and then examined whether FG-labeled neurons were substance P (SP)-immunoreactive or isolectin B4 (IB4)-binding. Of the FG-labeled neurons, 44.0% were immunoreactive for SP, whereas only 0.6% were reactive for IB4. The rate of SP-immunoreactive neurons was significantly higher than that of IB4-binding neurons (P<0.001), suggesting that under physiological conditions the dorsal portion of the lumbar disc is mainly innervated by peptide-containing neurons.     

Spatial distribution of mineralized bone matrix produced by marrow mesenchymal stem cells in self-assembling peptide hydrogel scaffold

We evaluated the osteogenic differentiation of mesenchymal stem cells (MSCs) using a new class of synthetic self-assembling peptide hydrogels, RADA 16, as a scaffold for three-dimensional culture. MSCs derived from rat bone marrow were culture-expanded and seeded into the hydrogel and further cultured in osteogenic medium containing beta-glycerophosphate, ascorbic acid, and dexamethasone for 2-4 weeks. High alkaline phosphatase activity and osteocalcin (OC) contents were detected at both the protein and gene expression levels during the culture periods. Both calcium and the OC contents increased over time, indicating the growth of a mineralized extracellular matrix within the hydrogel. Moreover, the process of the growth of the mineralized matrix determined by three-dimensional microarchitecture images was obtained by confocal laser scanning microscopy. The findings show that MSCs can differentiate into mature osteoblasts to form mineralized matrices within the hydrogel scaffold. Importantly, the differentiation can occur three dimensionally within the hydrogel, indicating that RADA 16 can be considered attractive synthetic biomaterial for use in bone tissue engineering.     

Spatial distribution of mast cells around vessels and glands in human gastric carcinoma

The spatial distribution of mast cells inside the tumor stroma has been little investigated. In this study, we have evaluated tumor mast cells (MCs) distribution in gastric cancer through the analysis of the morphological features of the spatial patterns generated by these cells, including size, shape, and architecture of the cell pattern. The pattern of distribution of tryptase- and chymase-positive MCs around the blood vessels and gastric glands in human gastric adenocarcinoma samples was investigated by immunohistochemical techniques and by introducing a quantitative approach to characterize the spatial distribution of MCs. In human gastric cancer, both chymase-positive MC and vessels exhibited significant deviations from randomness for what it concerns their spatial relationship with gastric parenchyma. As indicated by cell-to-gland distances shorter than expected by chance, in grade II samples a preferential localization of chymase-positive MC near the gastric glands was observed. Interestingly, the same type of spatial association was exhibited by vessels in grade IV samples, where vessel-to-gland distances shorter than expected by chance were observed. These two findings allow to speculate about a sequence of events in which a subpopulation of MC is first recruited around gastric parenchyma to drive the subsequent development of a vascular support to the tissue.     

Spatial distribution of muscle fibers

The analysis of Gates and Betz (1993 Anat. Rec., 236:381–389) of the spatial distribution of two different populations of muscle fibers in the lumbrical muscle of the rat is discussed. The conclusion that muscle fibers belonging to a single motor unit are distributd at random in most muscles appears to need reconsideration. A new technique is applied to some examples to show that the amount of clustering of fiber types in a muscle cross section can be quantified. © 1995 Wiley-Liss, Inc.